The same-sex marriage referendum captured the imagination of Ireland and the world, becoming the most talked-about topic of 2015 here, according to new data released by Facebook.

The social network, which has over two million users in Ireland, has released the results of the most commented-on, posted-about and 'liked' issues of the year.

Top of the list was Ireland's historic marriage-equality referendum, followed by the Syrian refugee crisis as the next most-discussed topic.

St Patrick's Day, the UK general election and the Paris terror attacks were the next most talked-about topics here, while the Greek debt crisis came in sixth.

Tourist destinations dominated the most talked-about places in Ireland, with the Guinness Storehouse and Brewery pipping the Cliffs of Moher for top spot in our Facebook discussions.

Globally, the US presidential election was the most talked-about topic, despite there still being a year to go to election day.

The world's most talked-about entertainer list was topped by Ed Sheeran, followed by Taylor Swift, Kanye West, Nicky Jam and rapper Wiz Khalifa.

Meanwhile, 'Game of Thrones' ruled the small screen as the most talked-about TV show, while 'Star Wars: The Force Awakens' led the list of most talked-about movies.

Facebook said it totted up the popularity of topics and places by measuring how frequently a topic was mentioned in Facebook posts made between January 1 and December 1 of this year.

However, it says that it did not compromise users' privacy and that posts "were analysed in an aggregated, anonymised way" before being ranked.

Separately, YouTube released its own list of the most popular videos Irish people watched.

The top trending video was by cosmetics brand Always with its #LikeaGirl campaign. Other top spots were occupied by Conor McGregor and an interview conducted by RTÉ broadcaster Ray D'Arcy of a Jack Nicholson impersonator, Norman Deesing.

YouTube also unveiled the top music videos viewed in Ireland on the platform, with Wiz Khalifa, Ellie Goulding and Adele all making the top 5, followed by Taylor Swift, Rihanna and Justin Bieber.